The application range of a touch function which has become a necessary function for most mobile devices has expanded to input devices of home appliances. A time of battery use, which is one of the most important specifications of a mobile product, is determined by the power consumptions of the respective parts of the mobile product. Thus, touch products mounted on mobile products must be designed as low-power consumption products.
Furthermore, with the enhancement in performance of mobile products, consumers using the mobile products have requested a very complex and delicate touch input function.
During a normal operation for calculating the coordinate of an external touch on a touch panel, existing products perform a scanning operation on the entire touch panel by performing a scanning operation for each line.
FIG. 1 is a diagram for describing a scanning method for a touch panel in conventional touch products.
As illustrated in FIG. 1, the touch panel 104 for the conventional touch products includes driving lines 101 serving as horizontal lines and input lines 102 serving as vertical lines.
In the method for scanning the touch panel for the conventional touch products, an operation of driving a driving voltage to one driving line and then reading values of all input lines is referred to as a single scan. Furthermore, a single scan for one line is performed several times according to a value set by a touch controller 105. Such a scan is referred to as a line scan. Furthermore, the line scan is sequentially or randomly performed on all driving lines. Such a scan is referred to as a frame scan 103.
In general, the touch controller drives the driving lines in order of the single scan, the line scan, and the frame scan. Then, the touch controller reads the state of the touch panel by reading the values of the input lines. The touch controller may perform the frame scan in a different order from the above-described order. However, in order to finally read the state of the panel, the touch controller repetitively drives nodes within the touch panel by a required number of times, and reads the values of the nodes.
The read values of the panel nodes are used for calculating a coordinate of an external touch object according to various arithmetical operations, a filter function, and a location tracking algorithm. Such internal arithmetic operation functions of the touch controller are designed to be performed during one frame.
Thus, the frame scan operation and the internal arithmetic operations may be designed to have a period within one frame, and performed at the same time. Such a method minimizes the operating time of one frame. The operating time of one frame in the operation of the touch panel determines the speed of touch response to an external touch. The touch response speed is an important factor for evaluating the performance of the touch panel.
One frame period which determines the touch response speed as an important factor for evaluating the performance of the touch panel is set according to the number of driving lines, the repeat count, and the calculation amount of the touch controller.
An interval between the driving lines is set according to the size of a touch object of which a touch can be sensed, and the number of driving lines is set by dividing the size of the entire panel by the interval between the driving lines. Thus, the number of driving lines cannot be reduced in order to simply increase the touch response speed.
The repeat count for each line is set according to the relation with noise generated in the panel. When the repeat count for the line scan is reduced, the touch response speed is increased, but noise is also increased. Thus, it is difficult to reduce the repeat count for the line scan, in order to increase the touch response speed.
Since the internal calculation amount of the touch controller is set according to the number of the driving lines, the repeat count, and the number of the input lines, it is also difficult to reduce the internal calculation amount, because of the above-described reasons.
Therefore, since the touch response speed cannot be improved through the conventional scanning method, this situation may cause a problem in which a touch operation responds slower than an actual operation. Furthermore, since the internal calculation amount for the panel scan and the touch coordinate calculation is not reduced, power consumption cannot be reduced.